Observations on the Daily Fluctuation in Flower Visiting Activity of Smaller Green Flower Chafer, Oxycetonia jucunda Faldermann on Citrus Flowers

Abstract

Daily changes in the flower visiting activity of smaller green flower chafer, Oxycetonia jucunda Faldermann and some other flower visiting insects on citrus flowers were observed in May 1969. The number of flower visiting individuals of green flower Chafer was most abundant in the daytime when the weather was fine. The beetles flew for citrus flowers from the outside of orchards. The numbers on flowers began to increase from 8.00~10.00 am. and showed its peak between 10.00~11.00 am. In the afternoon, the number gradually decreased. In the evening, almost all of them flew away but a few individuals stayed on the flowers during night. We could not observe the flying activity and daily changes in the numbers of this insect on citrus flowers in rainy days. Daily fluctuations in the sex ratio on flowers was examined. The ratio of the females increased in the daytime and decreased in the evening. It seemed that the male individuals have a tendency to stay on the flower throughout the day and night but females visit the flower in the daytime only. At the same time, daily fluctuation on the flowers of another beetle, Epuraea domina Reitter was observed. This species does not show any clear fluctuations in its number on flowers. This beetle seemes to stay on the flowers during the flowering season of citrus. © 1970, JAPANESE SOCIETY OF APPLIED ENTOMOLOGY AND ZOOLOGY. All rights reserved.